JPH09109275A - Lens centering and edging method and device thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To permit bell clamping for a lens with low curvature which is not capable of conducting ordinary bell clamp type centering and edging. SOLUTION: After centering is conducted through the first and second bell holders 1, 2 disposed so as to face each other coaxially, centering is conducted through the third and fourth bell holders 3, 4 disposed so as to move axially to fix a lens 11. The first and second bell holders 1, 3 are then retreated from a lens contact condition for centering and edging.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens centering method and apparatus used for molding an optical element by pressing a heated glass material with a pair of upper and lower molds.

[0002]

2. Description of the Related Art Glass press lens molding is mainly used for creating an aspherical surface, and the centering after molding can be centered by a conventional bell clamp as long as it has some curvature. There is a Z coefficient as an index for determining whether or not the centering by the bell clamp is possible, and it is defined as in Equation 1. In Equation 1, R1 and R2 are the radius of curvature of the lens, and r1 and r2 are the radii of the bell holder used for the bell clamp (see FIG. 10).

[0003]

(Equation 1)

On the other hand, recently, an aspherical lens used only for the purpose of removing the aberration of an optical system is used. In such an aspherical lens, a plane other than a necessary aspherical component is flat. , Has little curvature. Therefore, the curvatures R1 and R2 in the Z coefficient described above are close to infinity, and the value of Z is almost 0. Generally, the bell clamp centering possibility is Z ≧ 0.2
Therefore, such an aspherical lens cannot be centered by a bell clamp.

As a countermeasure, a centering method not using the bell clamp, that is, not using the curvature of the lens is used. . Japanese Unexamined Patent Publication No. 2-110501 performs this centering, and a stepped portion or a protruding thick portion provided coaxially with the center axis of curvature is formed on a press-molded lens material (generally called a pressed material). Centering is done by fitting a chuck to.

[0006]

However, the above-mentioned method has a drawback that the stepped portion or the protruding thick portion cannot be removed even after the centering and remains on the lens. Such unnecessary protrusions may be left if there is a margin in the design from the optical function surface (effective diameter) to the outer diameter after centering, but the effective diameter becomes the outer diameter as it is. This is not allowed, and there is a problem that centering cannot be performed.

The present invention has been made in consideration of the above problems of the prior art. For a lens having a shallow curvature in which bell clamp type centering is impossible, the centering is surely performed, Thus, it is an object of the present invention to provide a lens centering method and a device thereof that enable bell clamp centering.

[0008]

According to the lens centering method of the first aspect for achieving the above object, a curvature portion is provided on the outer circumference of the effective diameter portion coaxially with the rotational symmetry axis of the molding surface of the molding lens, and the curvature portion is It is characterized in that the bell holder is brought into contact with the center to perform centering.

According to this method, the curvature portion provided on the outer circumference of the effective diameter portion can be centered coaxially with the central axis by the centering action of the bell holder.

According to a second aspect of the present invention, after centering is performed by the first and second bell holders that are coaxially opposed to each other, the first and second bell holders are coaxial with each other and the inner diameter portion thereof is axially oriented. Centering is performed by the third and fourth holders arranged so as to be movable and fixed to the lens, and then the first and second bell holders are retracted from the lens contact state to perform centering processing. it can.

In this method, after performing centering by the first and second bell holders, a holder installed inside the bell holder is brought into contact with the bell holder to maintain the centered state, and then the first outside By moving the second bell holder away from the lens, it is possible to completely expose the curvature portion of the lens outer periphery used for centering, and thereby centering can be performed.

The centering device of the present invention comprises first and second bell holders that are coaxially opposed to each other, and third bells that are coaxially arranged on the inner diameters of the first and second bell holders. A fourth holder is provided, and the first to fourth holders are movable in the axial direction.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) FIGS. 1 to 5 show Embodiment 1 of the present invention, and FIG. 1 shows a state before centering of a glass press-molded lens 11. In the figure, d is the molded lens 11
The outer diameter, D _ED, is the effective diameter (optical function range), and D is the centering external dimension. Further, R1 and R2 are the radii of curvature of the outer peripheral curvature portions RA and RB, and when their ranges are A _RA and A _RB , they are provided so that d> A _RA −A _RB > D. The radii of curvature R1 and R2 must be designed so as to satisfy Z ≧ 0.2 when they are substituted into the Z coefficient described above.

FIG. 2 shows the tip of the holder of the centering device. Reference numerals 1 and 2 are bell holders, and holders 3 and 4 are coaxially arranged in the inner diameter portions thereof. The bell holders 1 and 2 and the holders 3 and 4 can be moved in the axial direction. Like the above-described R1 and R2, the tip diameters d1 to d2 of the bell holders 1 and 2 in contact with the lens are assumed to satisfy Z ≧ 0.2 when substituted into the Z coefficient. In this case, r1 = d1 / 2, r2 =
It is d2 / 2.

Next, the centering step according to this embodiment will be described. First, as shown in FIG. 3, the bell holders 1 and 2 are brought into contact with the curvature portions RA and RB of the molded lens 11. At this point, the central axis of the molded lens 11 and the central axes of the bell holders 1 and 2 are aligned, and the centering is completed.

Next, as shown in FIG. 4, the holders 3 and 4 inside the bell holders 1 and 2 are molded into the molded lens 1.
1 is approached and abutted to fix. Here, the bell holder 1 and the holder 3, and the bell holder 2 and the holder 4 are coaxially arranged. Therefore, the centering state by the bell holders 1 and 2 in FIG. 3 is also established between the holders 3 and 4 and the molded lens 11.

Then, as shown in FIG. 5, the bell holders 1 and 2 are retracted from the contact state with the molded lens 11. At this time, the molded lens 11 is clamped only by the holders 3 and 4, so that the outer peripheral curvature portions R1 and R2 of the molded lens are completely exposed to the centering device. As a result, the required external dimension D can be processed by centering.

By switching the holder to be clamped between the centering step and the centering step, the curved portion of the molded lens 11 used for the centering is completely exposed during the centering. It can be taken well. Therefore, centering can be performed on an aberration-removing lens having an extremely small Z coefficient, etc., with man-hours that are not significantly different from those of the ordinary bell clamp system.

(Embodiment 2) In this embodiment, one of the molded lenses for centering is a flat surface (R = ∞).
It shows the correspondence to the case. FIG. 6 shows a molded lens 12 to which this embodiment is applied. Molded lens 12 of FIG.
The molding function surface on the right side of is a flat surface, and this right surface does not have an outer peripheral curvature portion for centering.

FIG. 7 shows a lens mounting portion of a lens centering device for centering the molded lens 12. In this device, the holder 4 is not provided as compared with FIG. 2, and the bell holder 2 does not have an axial movement operation function. Moreover, the diameter d2 of the holder 2 is set to be smaller than the innermost diameter DS of the outer peripheral curvature portion of the molded lens 12.

In the above structure, the molded lens 12 is clamped by the bell holders 1 and 2 as shown in FIG. When the molded lens 12 is clamped by the bell holders 1 and 2, the outer peripheral curvature portion R provided on the left surface of the molded lens 12
A and the bell holder 1 contact each other, and the tip of the bell holder 1 contacts over the entire circumference, so that the central axes of the bell holders 1 and 2 are aligned with the central axis of the molded lens 12.

When this centering is completed, the holder 3 abuts and fixes the molded lens 12 as shown in FIG. Then, the bell holder 1 is retracted from the contact state with the molded lens 12, whereby the molded lens 12 is fixed by the bell holder 2 and the holder 3. In this state, the outer peripheral curvature portion R1 of the molded lens 12 is completely exposed, which allows processing to the required outer diameter D.

In such an embodiment, the outer peripheral curvature portion for centering is made to function only on one side, and the other points are the same as in the first embodiment. With such a structure, the clamp mechanism is simpler than that of the first embodiment, the device is simplified, its operation is facilitated, and the cost of the device can be reduced. It is.

[0024]

According to the centering method of the first aspect, the bell clamp type centering can be performed even for a lens having a shallow curvature which cannot be centered by the ordinary bell clamp type centering.

In the centering method of the second aspect, since the curved portion on the outer circumference of the lens can be completely exposed, the curved portion provided outside the effective diameter can be completely removed.

The centering device according to the third aspect can surely perform the above centering method.

[Brief description of the drawings]

FIG. 1 is a front view of a molded lens before centering according to a first embodiment.

FIG. 2 is a front view showing the arrangement of the holders according to the first embodiment.

FIG. 3 is a front view showing the first step of the first embodiment.

FIG. 4 is a front view showing a second step of the first embodiment.

FIG. 5 is a front view showing a third step of the first embodiment.

FIG. 6 is a front view of a molded lens of Embodiment 2 before centering.

FIG. 7 is a front view showing the arrangement of holders according to the second embodiment.

FIG. 8 is a front view showing a first step of the second embodiment.

FIG. 9 is a front view showing a second step of the second embodiment.

FIG. 10 is a front view of a lens for showing a Z coefficient.

[Explanation of symbols]

 1 2 Bell holder 3 4 Holder 11 Molded lens

Claims (3)

[Claims] 1. A lens centering method, wherein a curved portion is provided on an outer circumference of an effective diameter portion coaxially with a rotational symmetry axis of a molding surface of a molded lens, and a bell holder is brought into contact with the curved portion to perform centering. Method. 2. After centering by the first and second bell holders that are coaxially opposed to each other, the first and second bell holders can be coaxially moved with the first and second bell holders and can be axially moved to an inner diameter portion thereof. A lens core characterized by performing centering by the third and fourth holders arranged to fix the lens, and then withdrawing the first and second bell holders from the lens contact state to perform centering processing. How to take. 3. A first and second bell holders coaxially opposed to each other, and a third and a fourth holder coaxially arranged on an inner diameter portion of the first and second bell holders. A lens centering device, characterized in that the first to fourth holders are movable in the axial direction.